Understanding how a combi boiler works at your property

A combi boiler is designed to provide instantaneous hot water and heating when needed. It uses a heat exchanger to heat and direct water around your central heating system when the thermostat calls for heating demand or when a hot water tap is opened. 

For hot water, a valve inside the boiler diverts heat into the domestic hot water (DHW) supply when a hot water tap is turned on. This heat is supplied until the tap is turned back off again, when the valve is set back to the central heating position. 

The main benefit of a combi boiler is not only does it provide plentiful heat for central heating but also instantaneous hot water, from a single, compact appliance. This means that there is no need for a separate hot water cylinder, making combi boilers a cost effective solution that can save space and be situated in a convenient location. 

With a compatible thermostat, you can set heating times with a schedule to ensure efficiency and prevent heat being wasted. At Baxi, our boilers are all condensing models, which extract additional heat from the waste gases. By reusing this heat that would normally be lost makes the boiler more efficient.

Combi boilers are the most popular type of boiler sold in the UK and are suitable for most homes. There are, however, some considerations to have in mind to understand whether it will be the right solution for your needs.

 
For instance, if you have multiple bathrooms that could be using showers or taps all at the same time, the boiler will split the flow rate between all of them which ultimately slows it. In these instances, a system or heat only boiler may be an option, as it uses water stored in a hot water cylinder to meet the demand.